Production of high purity ethylbenzene from non-extracted feed and non-extracted reformate useful therein

ABSTRACT

A process for producing an ethylbenzene product having a purity of at least 99.50 percent based on the weight of ethylbenzene present in the product by the ethylation of the benzene present in non-extracted feed, e.g., non-extracted hydrocarbon composition. The non-extracted feed is substantially free of both C 4 − hydrocarbons and the C 7 + aromatic hydrocarbons and contains benzene and benzene coboilers. The process is carried out in the liquid phase, in the presence of an acid-active catalyst containing MCM-22 family molecular sieve, and under specified conditions.

FIELD OF THE INVENTION

This disclosure relates to a process for producing high purityethylbenzene by the ethylation of benzene present in non-extractedhydrocarbon composition feed.

BACKGROUND OF THE INVENTION

Ethylbenzene, C₈H₁₀, is a key raw material in the production of styreneand is produced by the ethylation reaction of ethylene, C₂H₄, andbenzene, C₆H₆, in a catalytic environment. When sold as a commodityproduct, the product will usually contain at least 99.95 weight percentof ethylbenzene based on the weight of the product.

A source of benzene is reformate, which is prepared by contacting amixture of petroleum naphtha and hydrogen with a reforming catalystcontaining a support, e.g., halogen-treated alumina or non-acidiczeolite L, and a hydrogenation/dehydrogenation metal, e.g., Group 8, 9,or 10 metal such as platinum. That process typically produces areformate that includes C₅− hydrocarbons, C₆-C₈ aromatic hydrocarbons,e.g., benzene, C₉+ hydrocarbons, C₆+ paraffins, and cycloparaffins(naphthenes).

Another source of benzene is the cracking of hydrocarbons such as bysteam cracking or catalytic cracking. That process typically produces aneffluent that includes C₆-C₈ aromatic hydrocarbons, e.g., benzene, C₆+paraffins, and naphthenes.

Still another source for producing aromatics is thedehydrocyclo-oligomerization of C₂-C₅ aliphatic hydrocarbons. Thatprocess typically produces a product effluent that includes C₆-C₈aromatic hydrocarbons, e.g., benzene, C₆+ paraffins, naphthenes and C₅aliphatic hydrocarbons.

Benzene can be separated from other reformate hydrocarbons, e.g., C₇+aromatics, by distillation. However, the benzene obtained bydistillation will usually contain C₆ and C₇ non-aromatic hydrocarbonimpurities that are difficult to separate from benzene by distillationbecause they have boiling points close to the boiling point of benzene,i.e., their boiling point is within 10° C. of benzene (boiling point of80.1° C.) at a pressure of about 101.3 kPa-a (absolute). This feed mayalso contain C₅ paraffins and naphthenes, such as n-pentane andcyclopentane. These impurities, which are hereinafter sometimes referredto as “benzene coboilers”, may be present in the distillate product inan amount up to 75 percent by weight based on the weight of the product.Examples of benzene coboilers include cyclohexane, methylcyclopentane,2-methylhexane, 3-methylhexane, 2,3-dimethylpentane,2,4-dimethylpentane, and dimethylcyclopentane.

The presence of these impurities during the ethylation of benzene canresult in an ethylbenzene product having less than desirable purity. Forexample, the presence of benzene coboilers during the ethylation ofbenzene can result in the formation of ethylbenzene coboilers(hydrocarbons having a boiling point within 10° C. of the boiling pointof ethylbenzene [boiling point of 136° C.] at a pressure of about 1 atm)that can not be easily removed from the ethylbenzene product bydistillation. It is well known, e.g., disclosed in U.S. Pat. Nos.5,258,569 and 5,221,777, that ethylbenzene coboilers can be formed byisoparaffin/olefin alkylation reactions.

Because of the deleterious effect of benzene coboilers, benzene obtainedby distillation usually undergoes an additional step, i.e., extractionsuch as liquid extraction or extractive distillation, to remove benzenecoboilers from the benzene product before the benzene is ethylated toform ethylbenzene. Generally, benzene used in the ethylation of benzeneto produce high purity ethylbenzene has a purity of about at least99.985 weight percent by weight based on the weight of benzene presentin the benzene distillate. However, the extraction step is expensive andtime consuming, which results in increased costs in manufacture of highpurity ethylbenzene.

By the present disclosure, a process is provided for ethylation ofbenzene to produce high purity ethylbenzene that uses feed containingbenzene that has not undergone extraction.

SUMMARY OF THE INVENTION

The present disclosure is directed to a process for producing anethylbenzene product having a purity of at least 99.50 percent based onthe weight of ethylbenzene present in the product using a hydrocarboncomposition feed that has not undergone extraction. The non-extractedhydrocarbon composition feed is substantially free of C₄− hydrocarbonsand C₇+ aromatic hydrocarbons, and contains benzene and from about 1 toabout 75 percent, from about 2 to about 75 percent, from about 3 toabout 75 percent, from about 5 to about 75 percent, or from about 10 toabout 75 percent, by weight of at least one C₆+ non-aromatic hydrocarbonhaving a boiling point within 10° C. at a pressure of about 101.3 kPa-aof the boiling point of benzene. The phrase “substantially free of C₄−hydrocarbons and C₇+ aromatic hydrocarbons” means that the hydrocarboncomposition feed contains less than about 0.05 percent by weight and,more preferably, less than about 0.01 percent by weight ofC₄−hydrocarbons and C₇+ aromatic hydrocarbons based on the weight of thehydrocarbon composition feed. The process is carried out by: (a)alkylating the benzene with ethylene in at least partial liquid phasewith an acid-active catalyst having an alpha value in a range from about1 to about 1000 at conditions that include a temperature in the range offrom about 162.8° C. to about 232.2° C., a pressure sufficient tomaintain the benzene in the liquid phase, usually at least 689.5 kPa-a,e.g., from about 689.5 kPa-a to about 6.89 MPa-a, a mole ratio ofethylene to benzene in the range of from about 0.001:1 to about 0.75:1,and a WHSV based on total ethylene over total catalyst for overallreactor in the range of from about 0.1 to about 10 hr¹; and (b)distilling the product of step (a) to produce an ethylbenzene producthaving a purity of at least 99.50 percent based on the weight ofethylbenzene present in the product.

In another embodiment, the present disclosure is directed to a processfor producing an ethylbenzene product having a purity of at least 99.50percent based on the weight of ethylbenzene present in the product froma hydrocarbon composition that comprises: (i) C₅− hydrocarbons; (ii)benzene; (iii) C₇+ aromatic hydrocarbons; and (iv) from about 1 to about75 percent by weight of at least one C₆+ non-aromatic hydrocarbon havinga boiling point within 10° C. at a pressure of about 101.3 kPa-a of theboiling point of benzene. The process is carried out by: (a) removingC₄− hydrocarbons and the C₇+ aromatic hydrocarbons from the reformate bydistillation to form the hydrocarbon composition; and (b) alkylating thebenzene present in the hydrocarbon composition of step (a) (withoutextraction of said reformate) with ethylene in at least partial liquidphase with a catalyst comprising at least one of a crystalline MCM-22family material and a zeolite beta molecular sieve at conditions thatinclude a temperature in the range of from about 162.8° C. to about232.2° C., a pressure sufficient to maintain the benzene in the liquidphase, usually at least 689.5 kPa-a, e.g., from about 689.5 kPa-a toabout 6.89 MPa-a, a mole ratio of ethylene to benzene in the range offrom about 0.001:1 to about 0.75:1, and a WHSV based on total ethyleneover total catalyst for overall reactor in the range of from about 0.1to about 10 hr¹; (c) distilling the product of step (b) to produce anethylbenzene product having a purity of at least 99.50 percent based onthe weight of ethylbenzene present in the product

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified process flow diagram, illustrating an embodimentof the disclosure.

FIG. 2 is a simplified process flow diagram, illustrating anotherembodiment of the disclosure.

FIG. 3 is a simplified process flow diagram, illustrating a furtherembodiment of the disclosure.

FIG. 4 is a graph plotting impurities present in the products of Test Aand Test B of the Example.

FIG. 5 is a graph illustrating aging of the catalyst used in Test A ofthe Example.

FIG. 6 is a gas chromatogram of impurities ethylbenzene coboilers formedby isoparaffin/olefin alkylation reactions.

DETAILED DESCRIPTION OF THE DISCLOSURE

All patents, patent applications, test procedures, priority documents,articles, publications, manuals, and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with the present disclosure and for all jurisdictions inwhich such incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.

As used in this specification, the term “framework type” is used in thesense described in the “Atlas of Zeolite Framework Types,” 2001.

As used herein, the numbering scheme for the Periodic Table Groups isused as in Chemical and Engineering News, 63(5), 27 (1985).

The term “aromatization”, as used herein, shall mean the production ofaromatics comprising benzene, toluene, or mixtures thereof by theconversion of non-aromatic hydrocarbons to aromatic hydrocarbonscomprising benzene, toluene, or mixtures thereof. The term“aromatization”, as used herein, shall also include the production ofaromatics comprising benzene, toluene, or mixtures thereof by thecracking of heavy aromatic hydrocarbons to produce the aromatichydrocarbons comprising benzene, toluene, or mixtures. Examples ofaromatization processes include catalytic reforming of naphtha,dehydrocyclo-oligomerization of C₂-C₅ aliphatic hydrocarbons, steamcracking of hydrocarbons to produce aromatic hydrocarbons comprisingbenzene, toluene, or mixtures thereof, and the catalytic cracking ofhydrocarbons to produce aromatic hydrocarbons comprising benzene,toluene, or mixtures thereof.

The term “reformate”, as used herein, shall mean the product produced by“aromatization”.

The term “C_(n)” hydrocarbon wherein n is an positive integer, e.g., 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, as used herein means a hydrocarbonhaving n number of carbon atom(s) per molecular. For example, C_(n)aromatics means an aromatic hydrocarbon having n number of carbonatom(s) per molecular; C_(n) paraffin means a paraffin hydrocarbonhaving n number of carbon atom(s) per molecular; C_(n) olefin means anolefin hydrocarbon having n number of carbon atom(s) per molecular. Theterm “C_(n)+” hydrocarbon wherein n is an positive integer, e.g., 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, as used herein means a hydrocarbonhaving at least n number of carbon atom(s) per molecular. The term“C_(n)−” hydrocarbon wherein n is an positive integer, e.g., 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, as used herein means a hydrocarbon having nomore than n number of carbon atom(s) per molecular.

As used herein, an “alkylatable aromatic compound” is a compound thatmay receive an alkyl group and an “alkylating agent” is a compound whichmay donate an alkyl group to an alkylatable aromatic compound. Oneexample of the alkylatable aromatic compounds is benzene. Examples ofthe alkylating agent are ethylene, propylene, polyalkylated aromaticcompound(s), e.g., di-ethylbenzene, tri-ethylbenzene,di-isopropylbenzene, and tri-isopropylbenzene

The term “wppm” as used herein is defined as parts per million byweight.

The term “at least partially in liquid phase” as used herein isunderstood as a mixture having at least 1 wt. % liquid phase, optionallyat least 5 wt. % liquid phase at a given temperature, pressure, andcomposition.

The term “substantially in liquid phase” as used herein is understood asa mixture having at least 95 wt. % liquid phase, optionally at least 99wt. % liquid phase at a given temperature, pressure, and composition.

The term “aromatic” as used herein is to be understood in accordancewith its art-recognized scope which includes alkyl substituted andunsubstituted mono- and polynuclear compounds. Compounds of an aromaticcharacter, which possess a heteroatom, are also useful providedsufficient activity can be achieved if they act as catalyst poisonsunder the reaction conditions selected.

The term “at least partially in liquid phase” as used herein isunderstood as a mixture having at least 1 wt. % liquid phase, optionallyat least 5 wt. % liquid phase at a given temperature, pressure, andcomposition.

The term “MCM-22 family material” (or “material of the MCM-22 family” or“molecular sieve of the MCM-22 family”), as used herein, includes:

-   -   (i) molecular sieves made from a common first degree crystalline        building block “unit cell having the MWW framework topology”. A        unit cell is a spatial arrangement of atoms which is tiled in        three-dimensional space to describe the crystal as described in        the “Atlas of Zeolite Framework Types”, Fifth edition, 2001, the        entire content of which is incorporated as reference;    -   (ii) molecular sieves made from a common second degree building        block, a 2-dimensional tiling of such MWW framework type unit        cells, forming a “monolayer of one unit cell thickness”,        preferably one c-unit cell thickness;    -   (iii) molecular sieves made from common second degree building        blocks, “layers of one or more than one unit cell thickness”,        wherein the layer of more than one unit cell thickness is made        from stacking, packing, or binding at least two monolayers of        one unit cell thick of unit cells having the MWW framework        topology. The stacking of such second degree building blocks can        be in a regular fashion, an irregular fashion, a random fashion,        and any combination thereof; or    -   (iv) molecular sieves made by any regular or random        2-dimensional or 3-dimensional combination of unit cells having        the MWW framework topology.

The MCM-22 family materials are characterized by having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 3.57±0.07and 3.42±0.07 Angstroms (either calcined or as-synthesized). The MCM-22family materials may also be characterized by having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15,3.57±0.07 and 3.42±0.07 Angstroms (either calcined or as-synthesized).The X-ray diffraction data used to characterize the molecular sieve areobtained by standard techniques using the K-alpha doublet of copper asthe incident radiation and a diffractometer equipped with ascintillation counter and associated computer as the collection system.Materials belong to the MCM-22 family include MCM-22 (described in U.S.Pat. No. 4,954,325), PSH-3 (described in U.S. Pat. No. 4,439,409),SSZ-25 (described in U.S. Pat. No. 4,826,667), ERB-1 (described inEuropean Patent No. 0293032), ITQ-1 (described in U.S. Pat. No.6,077,498), ITQ-2 (described in International Patent Publication No.WO97/17290), ITQ-30 (described in International Patent Publication No.WO2005118476), MCM-36 (described in U.S. Pat. No. 5,250,277), MCM-49(described in U.S. Pat. No. 5,236,575), MCM-56 (described in U.S. Pat.No. 5,362,697), and UZM-8 (described in U.S. Pat. No. 6,756,030). Theentire contents of the patents are incorporated herein by reference.

It is to be appreciated the MCM-22 family molecular sieves describedabove are distinguished from conventional large pore zeolite alkylationcatalysts, such as mordenite, in that the MCM-22 family materials have12-ring surface pockets which do not communicate with the 10-ringinternal pore system of the molecular sieve.

The zeolitic materials designated by the IZA-SC as being of the MWWtopology are multi-layered materials which have two pore systems arisingfrom the presence of both 10 and 12 membered rings. The Atlas of ZeoliteFramework Types classes five differently named materials as having thissame topology: MCM-22, ERB-1, ITQ-1, PSH-3, and SSZ-25.

The MCM-22 family molecular sieves have been found to be useful in avariety of hydrocarbon conversion processes. Examples of MCM-22 familymolecular sieve are MCM-22, MCM-49, MCM-56, ITQ-1, PSH-3, SSZ-25, andERB-1. Such molecular sieves are useful for alkylation of aromaticcompounds. For example, U.S. Pat. No. 6,936,744 discloses a process forproducing a monoalkylated aromatic compound, particularly ethylbenzene,comprising the step of contacting a polyalkylated aromatic compound withan alkylatable aromatic compound under at least partial liquid phaseconditions and in the presence of a transalkylation catalyst to producethe monoalkylated aromatic compound, wherein the transalkylationcatalyst comprises a mixture of at least two different crystallinemolecular sieves, wherein each of the molecular sieves is selected fromzeolite beta, zeolite Y, mordenite and a material having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15,3.57±0.07 and 3.42±0.07 Angstroms.

An embodiment of the present disclosure is depicted in FIG. 1. Referringto FIG. 1, naphtha is introduced via line 1 into reactor zone 3 wherethe naphtha is reformed or steam cracked into aromatic productsincluding benzene. Although only one reactor zone is shown, there can bemore than one reactor zone. In reactor zone 3, C₄− hydrocarbons areremoved from the reformate via line 4 and the remaining reformate iswithdrawn from reactor zone 3 via line 5 and introduced into column 7where the feed is fractionated to form a light reformate fraction, aheavy reformate fraction, and a benzene/benzene coboiler fraction. Thelight reformate fraction is withdrawn from column 7 through line 9, theheavy reformate fraction is withdrawn from column 7 through line 11, andthe benzene/benzene coboiler fraction is withdrawn from column 7 throughline 13 and introduced into zone 15. In zone 15, catalyst poisons, e.g.,sulfur, nitrogen, olefins, dienes, or combinations thereof are at leastpartially removed from the benzene/benzene coboiler fraction. Theresulting fraction is withdrawn from zone 15 via line 17 and introducedinto ethylation zone 18. In ethylation zone 18, ethylene is introducedvia line 19 and benzene is reacted with the ethylene to formethylbenzene. Low molecular weight molecules, such as ethylene andethane, are withdrawn from ethylation zone 18 via line 20. Theethylbenzene-containing product is withdrawn from ethylation zone 18 vialine 21 and introduced into column 23. In column 23, theethylbenzene-containing product is fractionated to form a C₇− fractionand a C₈+ fraction comprised of ethylbenzene and polyethylbenzenes. TheC₇− fraction is withdrawn from column 23 via line 25 and either removedfrom the unit via line 26 or recycled via line 17 to ethylation zone 18.The C₈+ fraction is withdrawn from column 23 via line 27 and introducedinto column 29 via line 27. In Column 29, the C₈+ fraction isfractionated to form a high purity ethylbenzene product fraction and aC₉+ fraction comprised of polyethylbenzenes. The high purityethylbenzene product fraction is withdrawn from column 29 via line 31and recovered without the need for further purification. Theethylbenzene product will usually have a purity that exceeds 99.50percent by weight based on the total weight of the product.

The remaining C₉+ fraction can undergo further processing. Asexemplified in FIG. 1, C₉+ fraction is withdrawn from column 29 via line33 and introduced into column 35. In column 35, polyethylbenzenes areseparated from C₁₃+ hydrocarbons. The C₁₃+ hydrocarbon fraction iswithdrawn from column 35 via line 36 and the polyethylbenzenes arewithdrawn from column 35 via line 38 and introduced into transalkylationzone 39. In transalkylation zone 39, the polyethylbenzenes aretransalkylated with benzene to form ethylbenzene. Benzene can beintroduced into transalkylation zone 39 via line 41 or the benzene canbe a fresh supply. The transalkylation product from transalkylation zone39 is transferred to column 23 via lines 43 and 21 for processing.

Another embodiment of the present disclosure is depicted in FIG. 2.Referring to FIG. 2, naphtha is introduced via line 51 into reactor zone53 where the naphtha is reformed into aromatic products includingbenzene. Although only one reactor zone is shown, there can be more thanone reactor zone. In reactor zone 53, C₄− hydrocarbons are removed fromthe reformate via line 55 and the remaining reformate is withdrawn fromreactor zone 53 via line 57 and introduced into column 59 where the feedis fractionated to form a light reformate fraction and a heavy reformatefraction. The light reformate fraction is withdrawn from column 59through line 61 and the heavy reformate fraction containing benzene andbenzene coboilers is withdrawn from column 59 through line 63, andintroduced into zone 65. In zone 65, olefins, dienes, or combinationsthereof are removed from the heavy reformate fraction. The resultingfraction is withdrawn from zone 65 via line 67 and introduced intocolumn 69 where the feed is fractionated to form a benzene/benzenecoboiler fraction and a C₇+ aromatic fraction. The C₇+ aromatic fractionis removed from column 69 fraction via line 71. The benzene/benzenecoboiler fraction is withdrawn from column 69 via line 73 and introducedinto ethylation zone 75. Ethylene is introduced into ethylation zone 75via line 77 and benzene is reacted with the ethylene to formethylbenzene. Low molecular weight molecules, such as ethylene andethane, are withdrawn from ethylation zone 75 via line 79. Theethylbenzene-containing product is withdrawn from ethylation zone 75 vialine 81 and introduced into column 83. In column 83, theethylbenzene-containing product is fractionated to form a C₇− fractionand a C₈+ fraction comprised of ethylbenzene and polyethylbenzenes. TheC₇− fraction is withdrawn from column 83 via line 85 and either removedfrom the unit via line 87 or recycled via line 73 to ethylation zone 75.The C₈+ fraction is withdrawn from column 83 via line 89 and introducedinto column 91. In Column 91, the C₈+ fraction is fractionated and formsa high purity ethylbenzene product fraction and a C₉+ fraction comprisedof polyethylbenzenes. The high purity ethylbenzene product fraction iswithdrawn from column 91 via line 93 and recovered without the need forfurther purification. The ethylbenzene product will usually have apurity that exceeds 99.50 percent by weight based on the total weight ofthe product.

The remaining C₉+ fraction can undergo further processing. Asexemplified in FIG. 2, C₉+ fraction is withdrawn from column 91 via line95 and introduced into column 97. In column 97, polyethylbenzenes areseparated from C₁₃+ hydrocarbons. The C₁₃+ hydrocarbon fraction iswithdrawn from column 97 via line 99 and the polyethylbenzenes arewithdrawn from column 97 via line 101 and transferred to transalkylationzone 103. In transalkylation zone 103, the polyethylbenzenes are reactedwith benzene to form ethylbenzene. Benzene can be introduced intotransalkylation zone 103 via line 105 or the benzene can be a freshsupply. The transalkylation product from transalkylation zone 103 istransferred to column 83 via lines 107 and 81 for processing.

A further embodiment of the present disclosure is depicted in FIG. 3.Referring to FIG. 3, naphtha having sufficient temperature is introducedvia line 111 into reactor zone 113 where the naphtha undergoes steamcracking resulting in a product containing aromatics including benzene.Although only one reactor zone is shown, there can be more than onereactor zone. In reactor zone 113, C₄− hydrocarbons are removed via line115 and a heavy fraction is removed via line 117. The fractioncontaining benzene and benzene coboilers is withdrawn from reactor zone113 via line 119 and introduced into zone 121 where the fraction ishydroprocessed to at least partially remove sulfur and nitrogen.Preferably, the fraction after treatment contains less than 5 wppm ofsulfur and less than 1 wppm of nitrogen. C₄− hydrocarbons are removedfrom zone 121 via line 123. The remaining fraction is removed from zone121 via 125 and transferred to column 127 where the feed is fractionatedto form a C₅− hydrocarbon fraction and C₆+ hydrocarbon fraction. The C₅−hydrocarbon fraction is withdrawn from column 127 via line 129. The C₆+hydrocarbon fraction is withdrawn from column 127 via line 131 andintroduced into zone 133 where the fraction is treated to at leastpartially remove dienes and olefins. After treatment, the fractionpreferably contains less than 2500 wppm of olefins and dienes. After thetreatments described above, the reformate will preferably besubstantially free of C₄− hydrocarbons and C₇+ aromatic hydrocarbons andcontain benzene; from about 1 to about 75 percent by weight based on theweight of the reformate, of at least one C₆+ non-aromatic hydrocarbonhaving a boiling point within 10° C. at a pressure of about 101.3 kPa-aof the boiling point of benzene; less than 5 wppm of sulfur; less than 1wppm of nitrogen; and less than 2500 wppm of olefins and dienes.

The fraction is then withdrawn from zone 133 via line 135 and introducedinto column 137 where the feed is fractionated to form a fractioncontaining benzene and benzene coboilers and a C₇+ aromatic fraction.The C₇+ aromatic fraction is removed from column 137 via line 139. Thebenzene/benzene coboiler fraction is withdrawn from column 137 via line141 and introduced into ethylation zone 143. Ethylene is introduced intoethylation zone 143 via line 145 and is reacted with the benzene to formethylbenzene. Low molecular weight molecules, such as ethylene andethane, are withdrawn from ethylation zone 143 via line 147.Ethylbenzene-containing product is withdrawn from ethylation zone 143via line 149 and introduced into column 151. In column 151, theethylbenzene-containing product is fractionated to form a C₇− fractionand a C₈+ fraction comprised of ethylbenzene and polyethylbenzenes. TheC₇− fraction is withdrawn from column 151 via line 153 and is eitherremoved via line 155 or recycled via line 141 to ethylation zone 143.The C₈+ fraction is withdrawn from column 151 via line 157 andintroduced into column 159. In Column 159, the C₈+ fraction isfractionated into a high purity ethylbenzene product fraction and a C₉+fraction comprised of polyethylbenzenes. The high purity ethylbenzeneproduct fraction is withdrawn from column 159 via line 161 and recoveredwithout need for further purification. The ethylbenzene product willusually have a purity that exceeds 99.50 percent by weight based on thetotal weight of the product.

The remaining C₉+ fraction can undergo further processing. Asexemplified in FIG. 3, the C₉+ fraction is withdrawn from column 159 vialine 163 and introduced into column 165. In column 165,polyethylbenzenes are separated from C₁₃+ hydrocarbons. The C₁₃+hydrocarbon fraction is withdrawn from column 165 via line 167 and thepolyethylbenzenes are withdrawn from column 165 via line 169 andtransferred to transalkylation zone 171. In transalkylation zone 171,the polyethylbenzenes are transalkylated with benzene to formethylbenzene. Benzene can be introduced into transalkylation zone 171via line 173 or the benzene can be a fresh supply. The transalkylationproduct of transalkylation zone 171 is transferred to column 151 vialines 175 and 149 for processing.

Ethylation Catalyst

In a preferred embodiment, the catalyst used in ethylating benzene willbe acid-active catalyst comprising a crystalline MCM-22 family material.These molecular sieves are described in detail in “Atlas of ZeoliteFramework Types”, eds. Ch. Baerlocher, W. H. Meier, and D. H. Olson,Elsevier, Fifth Revised Edition, 2001, which is hereby incorporated byreference. Examples of MCM-22 family molecular sieves include MCM-22,MCM-36, MCM-49, MCM-56, ITQ-1, SSZ-25, and PSH-3. Preferably, themolecular sieve is MCM-22, and, most preferably, the molecular sieve isaluminosilicate MCM-22.

The acid-active catalyst used in this disclosure will usually have analpha value in the range of from about 1 to about 1000, preferably fromabout 10 to about 1000, more preferably from about 100 to about 1000.

In some aspects, the acid-active catalyst used in this disclosure maycomprise a medium pore molecular sieve having a Constraint Index of 2-12(as defined in U.S. Pat. No. 4,016,218), including ZSM-5, ZSM-11,ZSM-12, ZSM-22, ZSM-23, ZSM-35, and ZSM-48. ZSM-5 is described in detailin U.S. Pat. Nos. 3,702,886 and Re. 29,948. ZSM-11 is described indetail in U.S. Pat. No. 3,709,979. ZSM-12 is described in U.S. Pat. No.3,832,449. ZSM-22 is described in U.S. Pat. No. 4,556,477. ZSM-23 isdescribed in U.S. Pat. No. 4,076,842. ZSM-35 is described in U.S. Pat.No. 4,016,245. ZSM-48 is more particularly described in U.S. Pat. No.4,234,231. The entire contents of all the above patent specificationsare incorporated herein by reference.

In some other aspects, the acid-active catalyst used in this disclosuremay comprise a large pore molecular sieve having a Constraint Index ofless than 2. Suitable large pore molecular sieves include zeolite beta,zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y), mordenite,ZSM-3, ZSM-4, ZSM-18, a MCM-22 family material, and ZSM-20. ZeoliteZSM-14 is described in U.S. Pat. No. 3,923,636. Zeolite ZSM-20 isdescribed in U.S. Pat. No. 3,972,983. Zeolite beta is described in U.S.Pat. No. 3,308,069, and Re. No. 28,341. Low sodium Ultrastable Ymolecular sieve (USY) is described in U.S. Pat. Nos. 3,293,192 and3,449,070. Dealuminized Y zeolite (Deal Y) may be prepared by the methodfound in U.S. Pat. No. 3,442,795. Zeolite UHP-Y is described in U.S.Pat. No. 4,401,556. Rare earth exchanged Y (REY) is described in U.S.Pat. No. 3,524,820. Mordenite is a naturally occurring material but isalso available in synthetic forms, such as TEA-mordenite (i.e.,synthetic mordenite prepared from a reaction mixture comprising atetraethylammonium directing agent). TEA-mordenite is disclosed in U.S.Pat. Nos. 3,766,093 and 3,894,104. The entire contents of all the abovepatent specifications are incorporated herein by reference.

In some embodiments, the acid-active catalyst may comprise a mixture ofat least one medium pore molecular sieve having a Constraint Index of2-12 and at least one large pore molecular sieve having a ConstraintIndex of less than 2.

The molecular sieve present in the catalyst will usually have an alphavalue in the range of from about 100 to about 1000. The alpha value is ameasure of molecular sieve acidic functionality and is describedtogether with details of its measurement in U.S. Pat. No. 4,016,218 andin J. Catalysis, Vol. VI, pp. 278-287 (1966) and reference is made tothese for such details. Higher alpha values correspond with a moreactive cracking catalyst.

The transalkylation catalyst may comprise a medium pore molecular sievehaving a Constraint Index of 2-12 (as defined in U.S. Pat. No.4,016,218), including ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, andZSM-48. ZSM-5, a large pore molecular sieve having a Constraint Index ofless than 2. Suitable large pore molecular sieves include zeolite beta,MCM-22 family material, zeolite Y, Ultrastable Y (USY), Dealuminized Y(Deal Y), mordenite, ZSM-3, ZSM-4, ZSM-18, and ZSM-20. or anycombination thereof.

The Constraint Index is a convenient measure of the extent to which analuminosilicate or molecular sieve provides controlled access tomolecules of varying sizes to its internal structure. For example,aluminosilicates which provide a highly restricted access to and egressfrom its internal structure have a high value for the constraint index,and aluminosilicates of this kind usually have pores of small size, e.g.less than 5 Angstroms. On the other hand, aluminosilicates which providerelatively free access to the internal aluminosilicate structure have alow value for the constraint index, and usually pores of large size. Themethod by which Constraint Index may be determined is described fully inU.S. Pat. No. 4,016,218, which is incorporated herein by reference.

Usually the crystalline molecular sieve will be combined with bindermaterial resistant to the temperature and other conditions employed inthe process. Examples of suitable binder material include clays,alumina, silica, silica-alumina, silica-magnesia, silica-zirconia,silica-thoria, silica-beryllia, and silica-titania, as well as ternarycompositions, such as silica-alumina-thoria, silica-alumina-zirconia,silica-alumina-magnesia and silica-magnesia-zirconia. The molecularsieve may also be composited with zeolitic material such as the zeoliticmaterials which are disclosed in U.S. Pat. No. 5,993,642, which ishereby incorporated by reference.

The relative proportions of molecular sieve and binder material willvary widely with the molecular sieve content ranging from between about1 to about 99 percent by weight, more preferably in the range of about10 to about 70 percent by weight of molecular sieve, and still morepreferably from about 40 to about 70 percent.

Aromatization

Aromatization will usually be carried out by thedehydrocyclo-oligomerization of C₂-C₅ aliphatics, catalytic reforming ofnaphtha, or the cracking of hydrocarbons.

Dehydrocyclo-oligomerization involves converting C₂-C₅ aliphatichydrocarbons to aromatic hydrocarbons. The process is carried out bycontacting C₂-C₅ aliphatic hydrocarbons in an aromatization zone and inthe presence of a catalyst suitable for dehydrocyclodimerization andunder conditions effective to produce an aromatics product comprisingbenzene and/or toluene. The dehydrocyclodimerization process increasescarbon chain length by oligomerization, promotes cyclization, anddehydrogenates cyclics to their respective aromatics.

The feedstream used in the dehydrocyclo-oligomerization process willcontain at least one aliphatic hydrocarbon containing 2 to about 5carbon atoms. The aliphatic hydrocarbons may be open chain, straightchain, or cyclic. Examples of such hydrocarbons include ethane,ethylene, propane, propylene, n-butane, n-butenes, isobutane, isobutene,butadiene, straight and branched pentane, pentene, and pentadiene.Dehydrocyclo-oligomerization conditions will vary depending on suchfactors as feedstock composition and desired conversion. A desired rangeof conditions for the dehydro-cyclodimerization of the aliphatichydrocarbons to aromatics include a temperature from about 350° to about750° C., a pressure from about 101.3 kPa-a to about 10.13 MPa-a, andweight hour space velocity from about 0.2 to about 8. It is understoodthat, as the average carbon number of the feed increases, a temperaturein the lower end of temperature range is required for optimumperformance and conversely, as the average carbon number of the feeddecreases, the higher the required reaction temperature.

The catalyst used in the dehydrocyclo-oligomerization reaction willpreferably comprise an intermediate pore size molecular sieve.Intermediate pore size molecular sieves have a pore size from about 5 toabout 7 Å and include, for example, AEL, AFI, MWW, MFI, MEL, MFS, MEI,MTW, EUO, MTT, HEU, FER, and TON structure type molecular sieves. Thesematerials are described in “Atlas of Zeolite Structure Types”, eds. W.H. Meier, D. H. Olson, and Ch. Baerlocher, Elsevier, Fourth Edition,1996, which is hereby incorporated by reference. Examples of suitableintermediate pore size molecular sieves include ZSM-5, ZSM-11, ZSM-12,ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50, ZSM-57, MCM-22,MCM-49, MCM-56, and SAPO-5. Preferred molecular sieves are SAPO-11, aswell as titanosilicate, gallosilicate, aluminosilicate, andgallium-containing aluminosilicate molecular sieves having a MFIstructure.

Usually the molecular sieve will be combined with binder materialresistant to the temperature and other conditions employed in theprocess. Suitable binder material and relative proportions of molecularsieve and binder material are the same as those described above for thecatalyst used for the propylation of benzene.

When the hydrocarbon composition feed used in the present disclosure ismade from reformate produced by catalytic reforming, the reformats willusually be formed by contacting a C₆+ paraffinic feed, e.g., naphtha,with a reforming catalyst under reforming conditions to produce areaction product comprising benzene and other hydrocarbons. Thereformate is formed under typical reforming conditions designed topromote dehydrogenation of naphthenes, isomerization of paraffinichydrocarbons and dehydrocyclization of non-aromatic hydrocarbons.

Substantially any hydrocarbon feed containing C₆+ paraffins, e.g.,naphtha, can be utilized as feedstock for naphtha reforming. The naphthawill generally comprise C₆-C₉ aliphatic hydrocarbons. The aliphatichydrocarbons may be straight or branched chain acyclic hydrocarbons, andparticularly paraffins such as heptane.

Catalysts suitable for use in catalytic reforming include acidicreforming catalysts (bifunctional catalysts) and non-acidic reformingcatalysts (monofunctional catalysts).

Acidic reforming catalysts usually comprise a metallic oxide supporthaving disposed therein a Group 8, 9, or 10 metal. Suitable metallicoxide supports include alumina and silica. Preferably, the acidicreforming catalyst comprises a metallic oxide support having disposedtherein in intimate admixture a Group 8, 9, or 10 metal (preferablyplatinum) and a metal promoter, such as rhenium, tin, germanium, cobalt,nickel, iridium, rhodium, ruthenium and combinations thereof. Morepreferably, the acidic reforming catalyst comprises an alumina support,platinum, and rhenium or platinum and tin on an alumina support.

Non-acidic or monofunctional reforming catalysts will comprise anon-acidic molecular sieve, e.g., zeolite, and one or morehydrogenation/dehydrogenation components. Examples of suitable molecularsieves include MFI structure type, e.g., silicalite, and molecularsieves having a large pore size, e.g., pore size from about 7 to 9Angstroms. Examples of large pore molecular sieves include LTL, FAU, and*BEA structure types. Examples of specific molecular sieves includezeolite L, zeolite X, zeolite Beta, zeolite Y, and ETS-10.

The reforming catalysts will contain one or morehydrogenation/dehydrogenation metals, e.g., Group 7 metals, such asrhenium, and Group 8, 9, or 10 metals, such as nickel, ruthenium,rhodium, palladium, iridium or platinum. The preferred Group 8, 9, or 10metal is platinum. Also, the nonacidic catalyst can contain a metalpromoter such as tin.

The amount of hydrogenation/dehydrogenation metal present on thenon-acidic catalyst will usually be from about 0.1% to about 5.0% ofhydrogenation/dehydrogenation metal based on the weight of the catalyst.The metal can be incorporated into the zeolite during synthesis of thezeolite, by impregnation, or by ion exchange of an aqueous solutioncontaining the appropriate salt. By way of example, in an ion exchangeprocess, platinum can be introduced by using cationic platinum complexessuch as tetraammine-platinum (II) nitrate.

The non-acidic catalyst will usually include a binder. The binder can bea natural or a synthetically produced inorganic oxide or combination ofinorganic oxides. Typical inorganic oxide supports which can be usedinclude clays, alumina, and silica, in which acidic sites are preferablyexchanged by cations that do not impart strong acidity.

The reforming process can be continuous, cyclic or semi-regenerative.The process can be in a fixed bed, moving bed, tubular, radial flow orfluid bed.

Conditions for reforming conditions include temperatures of at leastabout 400° C. to about 600° C. and pressures from about 344.7 kPa-a toabout 3.447 MPa-a, a mole ratio of hydrogen to hydrocarbons from 1:1 to10:1 and a liquid hour space velocity of between 0.3 and 10.

When the hydrocarbon composition feed used in the present disclosure ismade from reformate produced by steam cracking, the reformate willusually be formed by contacting a C₆+ paraffinic feed, e.g., naphtha,and steam under steam cracking conditions to produce a reaction productcomprising benzene and other hydrocarbons. The reformate is formed undertypical steam cracking conditions designed to promote thermal conversionof paraffins to light olefins and aromatics.

Substantially any hydrocarbon feed containing C₂+ paraffins, e.g.,ethane, propane, butanes, naphtha, distillate, atmospheric gas oil,vacuum gas oil, and/or any combination can be utilized as feedstock forsteam cracking. The naphtha will generally comprise C₆-C₉ non-aromatichydrocarbons. The non-aromatic hydrocarbons may be straight or branchedchain cyclic and acyclic hydrocarbons, and particularly cyclichydrocarbons such as methylcyclopentadiene.

The hydrocarbon composition will contain from about 1 to about 75percent by weight of at least one benzene coboiler, i.e., C₆+non-aromatic hydrocarbons having a boiling point within 10° C. at apressure of about 101.3 kPa-a of the boiling point of benzene. Somehydrocarbon compositions will contain different amounts of benzenecoboilers, e.g., about 5 to about 60 percent by weight of the at leastone benzene coboiler or from about 10 to about 50 percent by weight ofthe at least one benzene coboiler. Also in some hydrocarboncompositions, the C₆+ non-aromatic hydrocarbons present in thehydrocarbon composition will have a boiling point within 5° C. at apressure of about 101.3 kPa-a of the boiling point of benzene.

Examples of benzene coboilers that can be present in the hydrocarboncomposition feed to the propylation unit include cyclopentane,cyclohexane, methylcyclopentane, 2-methylhexane, 3-methylhexane,2,3-dimethylpentane, 2,4-dimethylpentane, and dimethylcyclopentane.

Feed Pretreatment

The hydrocarbon composition feed used in the process of the presentdisclosure may contain impurities such as, for example, olefins, dienes,sulfur-containing compounds, nitrogen-containing compounds, andcombinations thereof. Preferably, at least a portion of one or more ofthese impurities is removed from the hydrocarbon composition feed beforepropylation of benzene to extend the cycle length of the catalyst and toreduce the formation of ethylbenzene co-boilers in the product of thepropylation reactor.

Techniques for removing these impurities are known to persons skilled inthe art. Nitrogen-containing and sulfur-containing impurities can beremoved by hydroprocessing. Hydroprocessing techniques are well known inthe art and are often required to enable steam cracker naphtha to beblended into gasoline that meets U.S. low sulfur gasolinespecifications. Hydroprocessing is carried out by treating a hydrocarbonfeed with hydrogen in the presence of a supported catalyst athydrotreating conditions. The catalyst is usually comprised of a Group 6metal with one or more Group 8, 9, or 10 metals as promoters on arefractory support. In a preferred embodiment, steam cracker naphtha ishydrotreated to reduce sulfur levels to less than 5 wppm, nitrogenlevels to less than 1 wppm, and olefin and diene levels to less than2500 wppm. Hydroprocessing produces a naphtha from steam cracking withvery similar levels of impurities to the naphtha produced from naphthareforming. Techniques for subsequently removing the olefins and dienes(from either reformate or hydroprocessed steam cracker naphtha) aredisclosed in U.S. Pat. Nos. 6,781,023 and 6,500,996, which areincorporated by reference. A preferred technique for removing olefinsand dienes involves contacting the hydrocarbon composition feedcontaining olefins/dienes with a crystalline molecular sieve catalystcomprising MCM-22.

Nitrogen-containing and sulfur-containing impurities can also be removedby contacting the nitrogen-containing and sulfur-containing hydrocarboncomposition feed with an absorbent under absorption conditions effectiveto remove at least a portion of thenitrogen-containing/sulfur-containing impurities. Example of suitableabsorbents include clay materials and alumina compounds. Preferredabsorption conditions include a temperature of from ambient to 500° C.,more preferably from ambient to 200° C., or most preferably from ambientto 100° C.; a pressure sufficient to maintain liquid phase conditions; aweight hourly space velocity from 0.5 hr⁻¹ to about 100 hr⁻¹, morepreferably from about 0.5 hr⁻¹ to about 10 hr⁻¹, most preferably from1.0 hr⁻¹ to 4.0 hr⁻¹ depending upon the hydrocarbon composition feedbeing treated.

Process

Suitable alkylating agent(s) that may be used in this disclosurecomprise alkene compound(s), alcohol compound(s), and/oralkylbenzene(s), and mixtures thereof. Other suitable alkylating agentsthat may be useful in the process of this disclosure generally includeany aliphatic or aromatic organic compound having one or more availablealkylating aliphatic groups capable of reaction with the alkylatablearomatic compound. Examples of suitable alkylating agents comprise C₂olefin, viz., ethylene; C₂ alkanol; C₂ ethers, e.g., C₂-C₅ ethersincluding methylethylether and diethylether; aldehydes such asacetaldehyde; alkyl halides such as ethyl chloride; and polyalkylatedaromatic compound(s), e.g., bi-alkylated benzenes (e.g.,bi-ethylbenzene(s)) and tri-alkylated benzene(s) (e.g.,tri-ethylbenzenes), and so forth. Thus the alkylating agent maypreferably be selected from the group consisting of C₂, C₁-C₅ alkanols,bi-ethylbenzene(s), and tri-ethylbenzene(s). The alkylating agentincludes a concentrated alkene feedstock (e.g., polymer grade olefins)and a dilute alkene feedstock (e.g., catalytic cracking off-gas).

The alkylation reaction may also take place with the alkylatablearomatic compound and the alkylating agent in the reaction zone underconditions of at least partially in liquid phase. The alkylation ortransalkylation conditions include a temperature of 100 to 285° C.,preferably from about 162.8° C. to about 232.2° C., and a pressure of689 to 6.89 MPa-a, preferably, a pressure of 1500 to 3000 kPa-a, a WHSVbased on alkylating agent (e.g., alkene) for overall reactor of 0.1 to10 h⁻¹, preferably, 0.2 to 2 h⁻¹, more preferably, 0.5 to 1 h⁻¹, or aWHSV based on both alkylating agent and alkylatable aromatics foroverall reactor of 10 to 100 h⁻¹, preferably, 20 to 50 h⁻¹, a mole ratioof ethylene to benzene of from about 0.01:1 to about 0.5:1, and a WHSVbased on total ethylene over total catalyst for overall reactor of fromabout 0.5 and about 2 hr¹. More preferably, the mole ratio of ethyleneto benzene is in the range of from about 0.02:1 to about 0.4:1. Mostpreferably, mole ratio of ethylene to benzene is about 0.03. Thealkylatable aromatic compound is alkylated with the alkylating agent(e.g., alkene) in the presence of an alkylation or transalkylationcatalyst in a reaction zone or a plurality of reaction zones. Thereaction zone(s) are preferably located in a single reactor vessel, butmay include another reaction zone having an alkylation ortransalkylation catalyst bed, located in separate vessel which may be aby-passable and which may operate as a reactive guard bed. The catalystcomposition used in the reactive guard bed may be different from thecatalyst composition used in the reaction zone. The catalyst compositionused in the reactive guard bed may have multiple catalyst compositions.At least one reaction zone, and normally each reaction zone, ismaintained under conditions effective to cause alkylation of thealkylatable aromatic compound with the alkylating agent in the presenceof an alkylation or transalkylation catalyst.

Particular conditions for carrying out the alkylation of benzene withethylene at least partially in liquid phase may have a temperature offrom about 120 to 285° C., preferably, a temperature of from about 150to 260° C., a pressure of 689 to 4601 kPa-a, preferably, a pressure of1500 to 4137 kPa-a, a WHSV based on total ethylene and total catalystfor overall reactor of 0.1 to 10 h⁻¹, preferably, 0.2 to 2 h⁻¹, morepreferably, 0.5 to 1 h⁻¹, or a WHSV based on both total ethylene andbenzene, and total catalyst for overall reactor of 10 to 100 h⁻¹,preferably, 20 to 50 h⁻¹, and a molar ratio of benzene to ethylene fromabout 1 to about 100, preferably from about 20 to about 80.

In some embodiments, the benzene is alkylated with ethylene to produceethylbenzene in the liquid phase. Suitable liquid phase conditionsinclude a temperature between about 150° C. and 316° C., preferablybetween about 205° C. and 260° C., a pressure up to about 20875 kPa-a,preferably between 2860 and 5600 kPa-a, a space velocity between about0.1 and 20 h⁻¹ WHSV, preferably between 1 and 6 h⁻¹ WHSV, based on theethylene feed, and a ratio of the benzene to the ethylene in thealkylation reactor from about 0.5:1 to about 100:1 molar, preferably0.5:1 to 50:1 molar, more preferably from about 1:1 to about 30:1 molar,most preferably from about 1:1 to about 10:1 molar.

The alkylating agent, e.g., ethylene, to benzene ratios specified foruse in the process of the present disclosure refers to the mole ratio ofalkylating agent, e.g., ethylene, to benzene at the reactor inlet. Forexample, in case of a reactor having more than one catalyst bed, e.g.,four beds, with ethylene feed being injected into each bed, the moleratio of ethylene to benzene injected into each bed will be within thespecified range, i.e., ethylene to benzene mole ratio will be within arange defined by a lower number and a high number. For any specificrange defined by a lower number and a high number, the lower number willbe equal or lower than the higher end number, A range useful for thisdisclosure may be defined by any combination of two numbers selectedfrom the group consisting of 0.001:1, 0.01:1, 0.015:1, 0.2:1, 0.025:1,0.3:1; 0.31:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1,0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, and 1:1. Examples oftypical range are 0.001:1 to 0.75:1, 0.01:1 to 0.6:1; 0.02:1 to 0.5:1;0.02:1 to 0.4:1; 0.02:1 to 0.3:1; and 0.02:1 to 0.1:1.

The process of the present disclosure produces an ethylbenzene productthat contains at least 99.50 weight percent of ethylbenzene based on theweight of the product. Preferably, the process of the present disclosureproduces an ethylbenzene product that contains at least 99.65 weightpercent of ethylbenzene based on the weight of the product, morepreferably the ethylbenzene product has a purity of at least 99.85weight percent, and most preferably the ethylbenzene product has apurity of at least 99.95 weight percent. To further enhance the purityof the ethylbenzene product, the product can be blended with higherpurity ethylbenzene product. For example, an ethylbenzene product having99.85 weight percent purity can be increased to 99.985 weight percentpurity by blending appropriate amounts of higher purity ethylbenzeneproduct (100 percent ethylbenzene product) with the 99.85 purityproduct.

Distillation temperatures for separation, e.g., separation ofpolyethylbenzene from ethylbenzene, are known to persons skilled in theart and will depend upon the composition of thepolyethylbenzene/ethylbenzene product.

The process of the present disclosure includes recovery ofpolyethylbenzenes as a separate fraction followed by transalkylating thepolyethylbenzenes with benzene to form ethylbenzene.

The effluent from the reaction zone comprises the desired ethylbenzene,unreacted benzene, any unreacted ethylene (ethylene conversion isexpected to be at least 90 mol. %, preferably, about 98-99.9999 mol. %)and the alkane component and the other impurities. In one embodiment, atleast a portion of the effluent is fed to another reaction zone whereadditional ethylene is added for reaction with the unreacted benzenewith an alkylation catalyst. Furthermore, at least a portion theeffluent from any of the reaction zone(s) may be fed directly orindirectly to a transalkylation unit.

In addition to, and upstream of, the reaction zones, a by-passablereactive or unreactive guard bed may normally be located in a reactorseparate from the alkylation reactor. Such guard bed may also be loadedwith an alkylation or transalkylation catalyst, which may be the same ordifferent from the catalyst used in the reaction zone(s). Such guard bedis maintained from under ambient conditions, or at suitable alkylationor transalkylation conditions. At least a portion of benzene, andoptionally at least a portion of the ethylene, are passed through theunreactive or reactive guard bed prior to entry into the reaction zone.These guard beds not only serve to affect the desired alkylationreaction, but is also used to remove any reactive impurities in thehydrocarbon composition feeds, such as nitrogen compounds, which couldotherwise poison the remainder of the alkylation or transalkylationcatalyst. The catalyst in the reactive or unreactive guard bed maytherefore subject to more frequent regeneration and/or replacement thanthe remainder of the alkylation or transalkylation catalyst, and hencethe guard bed is typically provided with a by-pass circuit so that thealkylation feed(s) may be fed directly to the series connected reactionzones in the reactor while the guard bed is out of service. The reactiveor unreactive guard bed may be operated in co-current upflow or downflowoperation.

The reaction zone(s) used in the process of the present invention istypically operated so as to achieve essentially complete conversion ofthe ethylene. However, for some applications, it may be desirable tooperate at below 100% ethylene conversion. The employment of a separatefinishing reactor downstream of the reaction zone(s) may be desirableunder certain conditions. The finishing reactor would also containalkylation or transalkylation catalyst, which could be the same ordifferent from the catalyst used in other reaction zones in thealkylation or transalkylation reactor(s) and may be maintained under atleast partially liquid phase or alternately vapor phase alkylation ortransalkylation conditions. The polyalkylated aromatic compounds in theeffluents may be separated for transalkylation with alkylatable aromaticcompound(s). The alkylated aromatic compound is made by transalkylationbetween polyalkylated aromatic compounds and the alkylatable aromaticcompound.

The alkylation or transalkylation reactor(s) used in the process of thepresent invention may be highly selective to the desired monoalkylatedproduct, such as ethylbenzene, but typically produces at least somepolyalkylated species. In one embodiment, at least a portion of theeffluent from the final alkylation reaction zone is subjected to aseparation step to recover polyalkylated aromatic compound(s). Inanother embodiment, at least a portion of the polyalkylated aromaticcompound is supplied to a transalkylation reactor which may be separatefrom the alkylation reactor. The transalkylation reactor produces aneffluent which contains additional monoalkylated product by reacting thepolyalkylated species with an alkylatable aromatic compound. At least aportion of these effluents may be separated to recover the alkylatedaromatic compound (monoalkylated aromatic compound and/or polyalkylatedaromatic compound).

Where the alkylation system includes a reactive guard bed, it ismaintained under at least partial in liquid phase conditions. The guardbed will preferably operate at a temperature of from about 120 to 285°C., preferably, a temperature of from about 150 to 260° C., a pressureof 689 to 4601 kPa-a), preferably, a pressure of 1500 to 4137 kPa-a, aWHSV based on total ethylene and the total amount of catalyst for theoverall reactor of 0.1 to 10 h⁻¹, preferably, 0.2 to 2 h⁻¹, morepreferably, 0.5 to 1 h⁻¹, or a WHSV based on both total ethylene andtotal benzene, and the total amount of catalyst for the overall reactorof 10 to 100 h⁻¹, preferably, 20 to 50 h⁻¹, and a molar ratio of benzeneto ethylene from about 1 to about 100, preferably from about 20 to about80.

The transalkylation reaction may take place under at least partially inliquid phase conditions. Particular conditions for carrying out the atleast partially in liquid phase transalkylation of polyalkylatedaromatic compound(s), e.g., polyisopropylbenzene(s), with benzene mayinclude a temperature of from about 100° to about 300° C., a pressure of696 to 4137 kPa-a, a WHSV based on the weight of the polyalkylatedaromatic compound(s) feed to the alkylation reaction zone of from about0.5 to about 100 hr⁻¹ and a molar ratio of benzene to polyalkylatedaromatic compound(s) of from 1:1 to 30:1, preferably, 1:1 to 10:1, morepreferably, 1:1 to 5:1.

In another embodiment, the transalkylation reaction may take place undervapor phase conditions. Particular conditions for carrying out the vaporphase transalkylation of polyalkylated aromatic compound(s),polyisopropylbenzene(s), with benzene may include a temperature of fromabout 350 to about 450° C., a pressure of 696 to 1601 kPa-a, a WHSVbased on the weight of the polyalkylated aromatic compound(s) feed tothe reaction zone of from about 0.5 to about 20 hr⁻¹, preferably, fromabout 1 to about 10 hr⁻¹, and a molar ratio of benzene to polyalkylatedaromatic compound(s) of from 1:1 to 5:1, preferably, 2:1 to 3:1.

In some embodiments, this disclosure relates to:

-   1. A process for producing an ethylbenzene product having a purity    of at least 99.50 percent based on the weight of cumene present in    the product using a hydrocarbon composition feed that has not    undergone extraction, is substantially free of C₄− hydrocarbons and    C₇+ aromatic hydrocarbons, and contains benzene and from about 1 to    about 75 percent by weight of at least one C₆+ non-aromatic    hydrocarbon having a boiling point within 10° C. at a pressure of    about 101.3 kPa-a of the boiling point of benzene, said process    comprising:    -   (a) alkylating the benzene with ethylene in an alkylation        reaction zone, said reaction zone is maintained under at least        partial liquid phase conditions, with an acid-active catalyst at        conditions that include a temperature in the range of from about        125° C. to about 285° C., a pressure sufficient to maintain the        mixture of benzene and ethylene in at least partial liquid        phase, a mole ratio of ethylene to benzene in the range of from        about 0.001:1 to about 0.75:1, and a WHSV based on total        ethylene over total catalyst for overall reactor in the range of        from about 0.1 to about 10 hr¹; and    -   (b) distilling the product of step (a) to produce an        ethylbenzene product having a purity of at least 99.50 percent        based on the weight of ethylbenzene present in said ethylbenzene        product.-   2. The process recited in Paragraph 1, wherein said hydrocarbon    composition feed is produced from a reformate.-   3. The process recited in Paragraph 2, wherein said reformate    comprises: (i) C₅− hydrocarbons; (ii) benzene; (iii) C₇+ aromatic    hydrocarbons; and (iv) from about 1 to about 75 percent by weight of    at least one C₆+ non-aromatic hydrocarbon having a boiling point    within 10° C. at a pressure of about 101.3 kPa-a of the boiling    point of benzene and said hydrocarbon composition feed is prepared    from said reformate by removing by distillation the C₄− hydrocarbons    and said C₇+ aromatic hydrocarbons from said reformate.-   4. The process as recited in any preceding paragraph, further    comprising recovering polyethylbenzenes from the product of step    (a).-   5. The process as recited in Paragraph 4, further comprising    transferring said polyethylbenzenes to a transalkylation zone and    reacting the polyethylbenzenes with benzene under transalkylation    conditions to form ethylbenzene.-   6. The process as recited in Paragraph 5, wherein said ethylbenzene    produced by the reaction of the polyethylbenzenes with benzene is    transferred to said alkylation reaction zone.-   7. The process as recited in Paragraph 5, wherein said benzene is    reacted with polyethylbenzenes in said transalylation zone is    supplied from said hydrocarbon composition feed.-   8. The process recited in any preceding paragraph, wherein the    alkylation conditions include a temperature of from about 182° C. to    about 216° C., a pressure of from about 1479.6 kPa-a to about 2858.6    kPa-a, a mole ratio of ethylene to benzene of from about 0.01:1 to    about 0.5:1, and a WHSV based on total ethylene over total catalyst    for overall reactor of from about 0.5 and about 2 hr¹.-   9. The process recited in Paragraph 8, wherein said mole ratio of    ethylene to benzene is from about 0.02:1 to about 0.4:1.-   10. The process recited in Paragraph 9, wherein said mole ratio of    ethylene to benzene is about 0.03.-   11. The process as recited in any preceding paragraph, wherein said    acid active catalyst comprises at least one of a MCM-22 family    material and a zeolite beta molecular sieve.-   12. The process as recited in any preceding paragraph, wherein said    catalyst further comprises a binder.-   13. The process as recited in Paragraph 12, wherein said MCM-22    family material is selected from the group consisting of MCM-22,    MCM-36, MCM-49, and MCM-56.-   14. The process as recited in any preceding paragraph, wherein said    at least one C₆+ non-aromatic hydrocarbon is selected from the group    consisting of cyclohexane, methylcyclopentane, 2-methylhexane,    3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane,    dimethylcyclopentane, and mixtures thereof.-   15. The process recited in any preceding paragraph, wherein said    purity of said ethylbenzene product is at least 99.85 percent based    on the weight of ethylbenzene present in the product.-   16. The process recited in Paragraph 15, wherein said purity of said    ethylbenzene product is at least 99.985 percent based on the weight    of ethylbenzene present in the product.-   17. The process recited in any one of Paragraphs 2-16, wherein said    reformate is formed by the catalytic reforming of naphtha.-   18. The process recited in any one of Paragraphs 2-16, wherein said    reformate is formed by the cracking of hydrocarbons.-   19. The process recited in Paragraph 18, wherein said cracking is    accomplished by steam cracking.-   20. The process as recited in any preceding paragraph, wherein said    at least one C₆+ non-aromatic hydrocarbon is present in said    hydrocarbon composition feed in an amount 5 to about 60 percent by    weight of at least one C₆+ non-aromatic hydrocarbon having a boiling    point within 10° C. at a pressure of about 101.3 kPa-a of the    boiling point of benzene.-   21. The process as recited in Paragraph 20, wherein said at least    one C₆+ non-aromatic hydrocarbon is present in said hydrocarbon    composition feed in an amount 10 to about 50 percent by weight of at    least one C₆+ non-aromatic hydrocarbon having a boiling point within    10° C. at a pressure of about 101.3 kPa-a of the boiling point of    benzene.-   22. The process as recited in any preceding paragraph, wherein said    hydrocarbon composition feed contains impurities selected from the    group consisting of olefins, dienes, sulfur-containing compounds,    nitrogen-containing compounds, and mixtures thereof and at least a    portion of at least one of said impurities are removed from the feed    prior to contact with said catalyst.-   23. A process for producing an ethylbenzene product having a purity    of at least 99.50 percent based on the weight of ethylbenzene    present in the product using a hydrocarbon composition that has not    undergone extraction, said process comprising:    -   (a) providing a reformate that comprises: (i) C₅−        hydrocarbons; (ii) benzene; (iii) C₇+ aromatic hydrocarbons;        and (iv) from about 1 to about 75 percent by weight based on the        weight of the reformate of at least one C₆+ non-aromatic        hydrocarbon having a boiling point within 10° C. at a pressure        of about 101.3 kPa-a of the boiling point of benzene;    -   (b) removing C₄− hydrocarbons and the C₇+ aromatic hydrocarbons        from the reformate by distillation to form a hydrocarbon        composition;    -   (c) alkylating the benzene present in the hydrocarbon        composition without extraction of the hydrocarbon composition        with ethylene in the liquid phase with a catalyst comprising at        least one of a MCM-22 family molecular sieve and a zeolite beta        molecular sieve at conditions that include a temperature in the        range of from about 163° C. to about 232° C., a pressure        sufficient to maintain the benzene in the liquid phase, usually        at least 0.79 MPa-a, e.g., from about 0.79 to about 6.995 MPa-a,        a mole ratio of ethylene to benzene in the range of from about        0.001:1 to about 0.75:1, and a WHSV based on total ethylene over        total catalyst for overall reactor in the range of from about        0.1 to about 10 h¹; and    -   (d) distilling the product of step (c) to produce an        ethylbenzene product having a purity of at least 99.50 percent        based on the weight of ethylbenzene present in the product.-   24. The process recited in Paragraph 23, wherein the alkylation    conditions include a temperature of from about 182° C. to about 216°    C., a pressure of from about 1479.6 kPa-a to about 2858.6 kPa-a, a    mole ratio of ethylene to benzene of from about 0.01:1 to about    0.65, and a WHSV based on total ethylene over total catalyst for    overall reactor of from about 0.5 and about 2 hr¹.-   25. The process recited in any one of Paragraphs 23-24, wherein said    mole ratio of ethylene to benzene is from about 0.02:1 to about    0.4:1.-   26. The process recited in Paragraph 25, wherein said mole ratio of    ethylene to benzene is about 0.03.-   27. The process as recited in any one of Paragraphs 23-26, wherein    said MCM-22 family molecular sieve is selected from the group    consisting of MCM-22, MCM-36, MCM-49, and MCM-56.-   28. The process as recited in any one of Paragraphs 23-27, wherein    said molecular sieve is MCM-22.-   29. The process recited in any one of Paragraphs 23-28, wherein said    reformate is formed by the catalytic reforming of naphtha.-   30. The process recited in any one of Paragraphs 23-28, wherein said    reformate is formed by the cracking of hydrocarbons.-   31. The process recited in Paragraph 30, wherein said cracking is    accomplished by steam cracking.-   32. The process recited in any one of Paragraphs 23-28, wherein said    purity of said ethylbenzene product is at least 99.85 percent based    on the weight of ethylbenzene present in the product.-   33. The process recited in any one of Paragraphs 23-28, wherein said    purity of said ethylbenzene product is at least 99.985 percent based    on the weight of ethylbenzene present in the product.-   34. The process as recited in any one of Paragraphs 23-33, wherein    said hydrocarbon composition feed contains impurities selected from    the group consisting of olefins, dienes, sulfur-containing    compounds, nitrogen-containing compounds, and mixtures thereof and    at least a portion of at least one of said impurities are removed    from the feed prior to contact with said catalyst.-   35. The process as recited in any one of Paragraphs 23-34, further    comprising recovering polyethylbenzenes from the product of step    (c).-   36. The process as recited in Paragraph 35, further comprising    transferring said polyethylbenzenes to a transalkylation zone and    reacting the polyethylbenzenes with benzene under transalkylation    conditions to form ethylbenzene.-   37. The process as recited in any one of Paragraphs 23-36, wherein    said at least one C₆+ non-aromatic hydrocarbon is present in said    hydrocarbon composition feed in an amount 5 to about 60 percent by    weight of at least one C₆+ non-aromatic hydrocarbon having a boiling    point within 10° C. at a pressure of about 101.3 kPa-a of the    boiling point of benzene.-   38. The process as recited in Paragraph 37, wherein said at least    one C₆+ non-aromatic hydrocarbon is present in said hydrocarbon    composition feed in an amount 10 to about 50 percent by weight of at    least one C₆+ non-aromatic hydrocarbon having a boiling point within    10° C. at a pressure of about 101.3 kPa-a of the boiling point of    benzene.

The following example illustrates certain embodiments of the presentdisclosure but is not intended to be construed as to be restrictive ofthe spirit and scope thereof.

EXAMPLE

Tests were carried out using a feed that comprised 49.5 weight percentbenzene and 49.5 percent by weight of 2,3-dimethylpentane (remainder ofthe feed contained other reformate produced hydrocarbons) by passing thefeed over a MCM-22 catalyst. The conditions of the first test (Test A)included a temperature from 176.7° C. to 204.4° C., a pressure of 1.72MPa-a, ethylene to benzene mole ratio of 0.5:1, and a WHSV based ontotal ethylene over total catalyst for overall reactor between 2 to 10hr¹. The conditions in the second test (Test B) included a temperaturefrom 176.7° C. to 204.4° C., a pressure of 1.72 MPa-a, ethylene tobenzene mole ratio of 1:1, and a WHSV based on total ethylene over totalcatalyst for overall reactor between 2 to 10 hr¹. Results of the testsare in FIG. 4 through FIG. 6.

FIG. 4 is a plot of impurities produced in the production ofethylbenzene vis à vis temperature and ethylene to benzene ratio andshows that the practice of the present disclosure resulted in theproduction of ethylbenzene product with low impurities. FIG. 5, which isa plot of the aging for the catalyst used in Test A, shows that processmonitoring is important to maintain production of high purityethylbenzene product. Impurities began increasing after about 14-15 dayson stream. After 25 days on stream, catalyst regeneration was conductedby contacting the catalyst with a hydrocarbon wash. FIG. 6 is a gaschromatogram of the impurities present in the ethylbenzene product afterthe catalyst was on stream for 25 days.

1. A process for producing an ethylbenzene product having a purity of atleast 99.50 percent based on the weight of cumene present in the productusing a hydrocarbon composition feed that has not undergone extraction,is substantially free of C₄− hydrocarbons and C₇+ aromatic hydrocarbons,and contains benzene and from about 1 to about 75 percent by weight ofat least one C₆+ non-aromatic hydrocarbon having a boiling point within10° C. at a pressure of about 101.3 kPa-a of the boiling point ofbenzene, said process comprising: (a) alkylating the benzene withethylene in an alkylation reaction zone, said reaction zone ismaintained under at least partial liquid phase conditions, with anacid-active catalyst at conditions that include a temperature in therange of from about 125° C. to about 285° C., a pressure sufficient tomaintain the mixture of benzene and ethylene in at least partial liquidphase, a mole ratio of ethylene to benzene in the range of from about0.001:1 to about 0.75:1, and a WHSV based on total ethylene over totalcatalyst for overall reactor in the range of from about 0.1 to about 10hr¹; and (b) distilling the product of step (a) to produce anethylbenzene product having a purity of at least 99.50 percent based onthe weight of ethylbenzene present in said ethylbenzene product.
 2. Theprocess recited in claim 1, wherein said hydrocarbon composition feed isproduced from a reformate.
 3. The process recited in claim 2, whereinsaid reformate comprises: (i) C₅-hydrocarbons; (ii) benzene; (iii) C₇+aromatic hydrocarbons; and (iv) from about 1 to about 75 percent byweight of at least one C₆+ non-aromatic hydrocarbon having a boilingpoint within 10° C. at a pressure of about 101.3 kPa-a of the boilingpoint of benzene and said hydrocarbon composition feed is prepared fromsaid reformate by removing by distillation the C₄− hydrocarbons and saidC₇+ aromatic hydrocarbons from said reformate.
 4. The process as recitedin claim 1, further comprising recovering polyethylbenzenes from theproduct of step (a).
 5. The process as recited in claim 4, furthercomprising transferring said polyethylbenzenes to a transalkylation zoneand reacting the polyethylbenzenes with benzene under transalkylationconditions to form ethylbenzene.
 6. The process as recited in claim 5,wherein said ethylbenzene produced by the reaction of thepolyethylbenzenes with benzene is transferred to said alkylationreaction zone.
 7. The process as recited in claim 5, wherein saidbenzene is reacted with polyethylbenzenes in said transalylation zone issupplied from said hydrocarbon composition feed.
 8. The process recitedin claim 1, wherein the alkylation conditions include a temperature offrom about 182° C. to about 216° C., a pressure of from about 1479.6kPa-a to about 2858.6 kPa-a, a mole ratio of ethylene to benzene of fromabout 0.01:1 to about 0.5:1, and a WHSV based on total ethylene overtotal catalyst for overall reactor of from about 0.5 and about 2 hr¹. 9.The process recited in claim 8, wherein said mole ratio of ethylene tobenzene is from about 0.02:1 to about 0.4:1.
 10. (canceled)
 11. Theprocess as recited in claim 1, wherein said acid-active catalystcomprises at least one of a MCM-22 family material and a zeolite beta.12. (canceled)
 13. (canceled)
 14. The process as recited in claim 1,wherein said at least one C₆+ non-aromatic hydrocarbon is selected fromthe group consisting of cyclohexane, methylcyclopentane, 2-methylhexane,3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane,dimethylcyclopentane, and mixtures thereof.
 15. The process recited inclaim 1, wherein said purity of said ethylbenzene product is at least99.85 percent based on the weight of ethylbenzene present in theproduct.
 16. (canceled)
 17. The process recited in claim 2, wherein saidreformate is formed by the catalytic reforming of naphtha. 18.(canceled)
 19. (canceled)
 20. The process as recited in claim 1, whereinsaid at least one C₆+ non-aromatic hydrocarbon is present in saidhydrocarbon composition feed in an amount 5 to about 60 percent byweight of at least one C₆+ non-aromatic hydrocarbon having a boilingpoint within 10° C. at a pressure of about 101.3 kPa-a of the boilingpoint of benzene.
 21. The process as recited in claim 20, wherein saidat least one C₆+ non-aromatic hydrocarbon is present in said hydrocarboncomposition feed in an amount 10 to about 50 percent by weight of atleast one C₆+ non-aromatic hydrocarbon having a boiling point within 10°C. at a pressure of about 101.3 kPa-a of the boiling point of benzene.22. The process as recited in claim 1, wherein said hydrocarboncomposition feed contains impurities selected from the group consistingof olefins, dienes, sulfur-containing compounds, nitrogen-containingcompounds, and mixtures thereof and at least a portion of at least oneof said impurities are removed from the feed prior to contact with saidcatalyst.
 23. A process for producing an ethylbenzene product having apurity of at least 99.50 percent based on the weight of ethylbenzenepresent in the product using a hydrocarbon composition that has notundergone extraction, said process comprising: (a) providing a reformatethat comprises: (i) C₅− hydrocarbons; (ii) benzene; (iii) C₇+ aromatichydrocarbons; and (iv) from about 1 to about 75 percent by weight basedon the weight of the reformate of at least one C₆+ non-aromatichydrocarbon having a boiling point within 10° C. at a pressure of about101.3 kPa-a of the boiling point of benzene; (b) removing C₄−hydrocarbons and the C₇+ aromatic hydrocarbons from the reformate bydistillation to form a hydrocarbon composition; (c) alkylating thebenzene present in the hydrocarbon composition without extraction of thehydrocarbon composition with ethylene in the liquid phase with acatalyst comprising at least one of a MCM-22 family material and azeolite beta molecular sieve at conditions that include a temperature inthe range of from about 163° C. to about 232° C., a pressure sufficientto maintain the benzene in the liquid phase, usually at least 0.79MPa-a, e.g., from about 0.79 to about 6.995 MPa-a, a mole ratio ofethylene to benzene in the range of from about 0.001:1 to about 0.75:1,and a WHSV based on total ethylene over total catalyst for overallreactor in the range of from about 0.1 to about 10 hr¹; and (d)distilling the product of step (c) to produce an ethylbenzene producthaving a purity of at least 99.50 percent based on the weight ofethylbenzene present in the product.
 24. (canceled)
 25. The processrecited in claim 24, wherein said mole ratio of ethylene to benzene isfrom about 0.02:1 to about 0.4:1.
 26. (canceled)
 27. The process asrecited in claim 24, wherein said molecular sieve is selected from thegroup consisting of MCM-22, MCM-36, MCM-49, and MCM-56.
 28. (canceled)29. The process recited in claim 23, wherein said reformate is formed bythe catalytic reforming of naphtha.
 30. (canceled)
 31. (canceled) 32.The process recited in claim 23, wherein said purity of saidethylbenzene product is at least 99.85 percent based on the weight ofethylbenzene present in the product.
 33. (canceled)
 34. The process asrecited in claim 23, wherein said hydrocarbon composition feed containsimpurities selected from the group consisting of olefins, dienes,sulfur-containing compounds, nitrogen-containing compounds, and mixturesthereof and at least a portion of at least one of said impurities areremoved from the feed prior to contact with said catalyst.
 35. Theprocess as recited in claim 23, further comprising recoveringpolyethylbenzenes from the product of step (c).
 36. The process asrecited in claim 35, further comprising transferring saidpolyethylbenzenes to a transalkylation zone and reacting thepolyethylbenzenes with benzene under transalkylation conditions to formethylbenzene.
 37. The process as recited in claim 23, wherein said atleast one C₆+ non-aromatic hydrocarbon is present in said hydrocarboncomposition feed in an amount 5 to about 60 percent by weight of atleast one C₆+ non-aromatic hydrocarbon having a boiling point within 10°C. at a pressure of about 101.3 kPa-a of the boiling point of benzene.38. (canceled)